1. Field of the Invention
This invention relates generally to devices for delivering a fine mist spray to cool an area by evaporative cooling, and more particularly concerns a fan propelled misting apparatus for providing a high velocity flow of air and a finely divided mist for evaporative cooling of wide areas.
2. Description of Related Art
While heated vaporizers provide humidifying vapors, atomizer type humidifiers typically generate a cooling mist. Such devices for providing a cooling mist are useful for efficiently and economically cooling large areas such as sections of outdoor amusement parks, and smaller areas such as a garden area, or even a single person. A portable misting device utilizing a pressurizable fluid tank and an atomizing nozzle for providing a finely divided water vapor mist is disclosed in U.S. Pat. No. 5,775,590, which is incorporated by reference herein.
Another type of conventional portable spray device provides a water spray, body massager, and a fan. Various types of cool mist humidifiers are also known that have a fan for distributing a mist. One high capacity device has a water driven fan that provides a water misted source of cool air for fighting fires. Another typical type of portable misting device includes a hand held spray applicator such as a spray bottle, and a low speed, fan, so that the device typically needs to be placed within a distance of four inches or less from the user, in order to achieve any significant cooling effect for the user.
It would be desirable to provide a cooling device that not only provides an evaporative cooling effect from the evaporation of a water mist, but also takes advantage of the wind chill effect that occurs when wind blows across a person's bare skin, and thereby removes heat. The wind chill effect is typically quantified as a wind chill equivalent air temperature that at a standard wind speed would produce the same heat loss as the given temperature and wind speed, as a measure of the cooling power of a given wind speed on a person's bare skin, at a given temperature. For example, a 35.degree. F. temperature wind speed of 5 MPH results in a wind chill equivalent air temperature of 33.degree. F.; a 35.degree. F. temperature wind speed of 10 MPH results in a wind chill equivalent air temperature of 22.degree. F.; and a 35.degree. F. temperature wind speed of 15 MPH results in a wind chill equivalent air temperature of 16.degree. F.
In order to increase the evaporative cooling effect of a water vapor mist, and to increase the wind chill effect, it would thus be desirable to provide a high speed air flow such as can be provided by a high speed fan. Small portable hand-held fans operating at about 6,000 RPM are known that can achieve a significant wind velocity at a close range such as about four inches or less, but such fans typically include blades that are low pitched and soft, and do not displace a sufficient amount of air to achieve a significant wind velocity at greater distances. In addition, the fanned air from such hand held fans readily disperses at a more convenient distance of about 18 inches from the fan, so that for delivery of such a cooling mist over distances of about 18 inches or greater, it would also be desirable to provide a generally laminar air flow for carrying and evaporating the mist, to allow such a laminar flow of air to resist dispersal while still efficiently mixing with a water vapor mist, achieving an effective wind chill factor to provide a more effective evaporative cooling from the water vapor mist before it is dispersed, and to reduce the power requirements and high velocities necessary to achieve a prolonged period of air flow about the water vapor mist. The present invention meets these needs.